Alloy



E. F. LOWRY Julie 21, 1938.

ALLOY Original Filed Oct. 50, 1929 0 0 0000 H wm5 a2 2 6% mum mdzbni LOwQZ m5O Increasing' Co baH'.

Increasing NicKel.

INVENTOR WITNESSES:

Patented June 21, 1938 PATENT oFFios ALLOY Erwin F. Lowry, Forest Hills,Pa., assignor to Westinghouse Electric & Manufacturing Company, acorporation of Pennsylvania Original application October 30, 1929,Serial No.

403,664. Divided and 1935, Serial No. 26,811

4 Claims.

The invention relates generally to improvements in cobalt, nickel alloysand the process of making them, and is a division of my copendingapplication Serial No. 403,664, filed October 30,

An object of the invention is to provide an alloy possessing theproperties of high tensile strength and high proportional (elastic)limit at high temperatures.

Another object of the invention is the provision of an alloy having highohmic resistance and capacity to resist oxidation at high temperatures.

It is also an object of the invention to provide an alloy which isductile and which may be readily forged.

Other objects of the invention will in part obvious and in part appearhereinafter.

The invention accordinglycomprises the several steps and the relationand order of one or more of such steps with respect to each of theothers, and the product possessing the features, properties, and therelation of constituents,

which are exemplified in the following detailed disclosure, and thescope of the application of which will be indicated in the claims.

For a' fuller understanding of the nature and objects of theinventiomreference should be had to the following detailed descriptiontaken in connection with the accompanying drawing, in

which the single figure shows a curve which gives the desired strengthof thealloy for different proportions of the ingredients.

The alloy is a cobalt nickel base alloy comprising cobalt and nickelwith the addition 01' some iron and one or more of the followingtitanium, tungsten, manganese, vanadium or molybdenum. The amounts ofthe ingredients added will be given in detail hereinafter.

. Alloys have been made containing'an aggre gate of to 95% nickel andcobalt. In these alloys desirable results were obtained with 95 to 5%nickel and from 5% to 95% cobalt, the remainder being iron and one ormore of the following titanium, tungsten, manganese, vanadium andmolybdenum.

While the proportions of the ingredients specifled hereinbefore havebeen found satisfactory, a very desirable alloy has been made with thecobalt in excess of the nickel. A suitable range is nickel from slightlybelow 40% to 10% and cobalt 40% to 85% plus iron and one or more of thefollowing titanium, tungsten manganese,

this application June 15,

suitable mixture which has been prepared is as follows:

Per cent 69.2 13.2 14.4

Cobalt Nickel Iron Titanium 2.5 Aluminum, manganese; silicon .7

In making the alloy the cobalt and nickel are first melted together insome suitable furnace in a reducing or inert atmosphere. An electricfurnace has been found to be satisfactory for melting the ingredients ofthe alloy. After the cobalt and nickel have been .melted the iron andadditional ingredients are added. In adding the iron, care should beexercised'to prevent oxygen in an appreciable volume from entering thefurnace.

In preparing the alloy it is good practice to add a small amount of adeoxidizer such as aluminum or magnesium to remove contained oxygen. Thedeoxidizer may be introduced in anysuitable manner such for example asby applying it to a silica rod and plunging it into the molten metals.

On the completion of these operations the molten alloy may be cast inpermanent molds. In order to prevent oxidation of the alloy, the moldsmay be coated with a heavy ofl.

It has been found good practice to pour the alloy rapidly into the moldsafter the temperature has been somewhat lowered from that to which ithas been heated to obtain good alloying. This method of introducing themetal into the'molds gives a smooth surface to the ingots which ishighly desirable.

The ingot thus prepared may be forged into bars of any predeterminedsize depending on the purposes for which the alloy is to be utilized.Generally, .in the primary forging operation the ingot should be heatedbut the temperature should not exceed 1100 C. In .some instances, tomeet predetermined conditions in forging operations, the temperature maybe raised a little higher, for example to 1150" C.

In order to make wires from the ingot it may be forged int bars ofsquare cross section of dimension. These bars may be readily rolled at atemperature of from 700 C. to 800 Ciinto bars having a. cross-sectionalarea of it" x A,. 50 These'bars may be subsequently cold rolled andswaged with frequent annealing at temperatures of .800" C. to 900 '0.into wires havin some predetermined diameter. The annealing should becarried out in a reducing or an inert 56 dies.

-ment having an oxide coat.

atmosphere such as hydrogen or nitrogen to prevent the formation of anoxide coating on the surface which would become embedded in the alloyduring the rolling operations.

After a wire of say 50 mils diameter has been made, it may be drawn downto any other required diameter by drawing it through diamond the drawingprocedure. Wires made from this alloy have a high ohmic resistance whichadapts them for the making of filaments for thermionic tubes and thelike.

In view of the strength which this alloy evidences at high temperatureait may be used for many purposes in thermionic devices. It lends itselfvery well to the manufacture of thermionic tubes which are provided witha fila- This alloy will receive the oxide coat and has the strength thatis desired at high temperatures.

Another important advantage of this type of alloy for the making offilaments for thermionic tubes is that when subjected to heatingtemperatures in the neighborhood of 1000 C. they have, when subjected tostresses, stood an elongation amounting to as much as 10% to 12% oftheir length before breaking. This makes unnecessary elaboratecompensating devices to provide for changes in size of the filament. Thefollowing table gives the physical characteristics of a representativealloy containing 58.6% cobalt, 20.6% nickel, 17.4% iron and 2.5%titanium and If -itis drawn through a number of dies, it maybe'necessary to anneal the wire during While I have described myinvention in considerable detail and given numerous illustrations, it isto be. understood that the preferred embodiments described in detailshould be construed as illustrative and not in a limiting sense, sincenumerous modifications may be made wiLhout departing from the spirit andscope of my invention, and it is desired that the claims be notinterpreted in a. limiting sense.

I claim as my invention:

1. A cobalt-nickel base alloy consisting of 40% to 85% cobalt and 40% to10% nickel aggregating from 80% -to 95% of the alloy and 20% to 5% ironand titanium, the titanium ranging from about 1% to 10%015 the alloy,the alloy having high tensile strength at high temperatures.

2. A cobalt-nickel alloy consisting of approximately 58.6% cobalt, 20.6%nickel, 17.4% iron and 2.5% titanium plus .9% impurities.

3. A cobalt-nickel base alloy consisting of cobalt and nickel in theaggregate amount of 80% to 95% by weight of the alloy, the cobaltranging from to 85% by weight and from 20% to 5% by weight iron and oneof the following,

titanium, manganese or vanadium, the metal selected from the group beingfrom 1% to 10% of the alloy.

4. A cobalt-nickel base alloy consisting of cobalt and nickel in theaggregate amount of 80% to 90% of the alloy, the cobalt ranging from 40%to and the nickel 15% to 40% and the balance being 20% to 5% iron andone or more of titanium, manganese, vanadium, the metal or nnwm F.LOWRY.

